Present day Christmas lighting and decorating is now done mostly by using light emitting diodes (LED's). LED light strings, with multiple LED's, are usually wired in electrical series and powered by rectified alternating current (A.C.). Some light strings are powered by half-wave rectification using a single rectifier diode while others are powered by full-wave rectified 120 volt A.C. yielding better brightness and less flicker. Since light emitting diodes are DC devices and emit light according to the voltage applied, any variation in voltage will cause a variation in brightness—thus flickering. This flicker is annoying to some people, even though at full-wave rectification it occurs 120 times per second.
To achieve low flicker in an LED light string, it is necessary to rectify the 120 volt A.C. supply voltage into D.C. (direct current) as ripple free as possible. This is usually done by using a full wave bridge rectifier circuit. However, for light strings with end-to-end connectors, this usually means four wires need to go “down the line”. In U.S. Pat. No. 6,972,528, Shao teaches a circuit in which the full wave rectifier is split into two groups—one group of two rectifiers connected at the front end of the string and the other group of two rectifiers connected at the end of the light string, i.e., a split bridge circuit. In U.S. Pat. Nos. 7,649,322 and 8,072,152, Neuman et al., teaches a similar split bridge approach, but uses an LED in series with each rectifier diode in the split bridge structure.